Multilouvered roughness silencer

ABSTRACT

A muffler has a plurality of open-ended perforated tubes mounted within a casing to extend parallel to a perforated straightthrough gas flow tube and arranged so that they provide expansion chambers that are fed by gas pulses emanating radially from the flow tube.

United States Patent Bert Du Bois Brooklyn, Mich. 58,396

July 27, 1970 Oct. 12, 1971 Tenneco Inc. Racine, Wis.

Inventor Appl. No. Filed Patented Assignee MULTILOUVERED ROUGHNESS SILENCER 7 Claims, 2 Drawing Figs.

US. Cl. 181/48, 1 18 1/63 Int. Cl. F0ln l/04, FOln 1/10 Field of Search 181/48 [56] References Cited UNITED STATES PATENTS 3,090,464 5/1963 naramer 181/54 ux 3,485,319 12/1969 Balluff l81/54X FOREIGN PATENTS 25,819 7/1936 Australia 181/48 841,834 6/1952 Germany... 181/59 1,058,791 6 1959 Germany... 181 48 1,242,940 6/1967 Germany 181/54 Primary Examiner- Robert S. Ward, Jr. Attorney-Harness, Dickey & Pierce ABSTRACT: A muffler has a plurality of open-ended perforated tubes mounted within a casing to extend parallel to a perforated straight-through gas flow tube and arranged so that they provide expansion chambers that are fed by gas pulses emanating radially from the flow tube.

MULTILOUVERED ROUGHNESS SILENCER BRIEF SUMMARY OF THE INVENTION It is the purpose of this invention to provide a low back pressure muffler containing a silencing structure similar in acoustic effect to that of a packed muffler, e.g. a muffler containing a gas flow tube extending through a mass of glass fiber.

The invention accomplishes this by means of a series of expansion chambers that are fed by transverse flow from the gas flow tube and provided by open-ended tubes mounted parallel to the flow tube.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal cross section of a muffler, shown somewhat schematically, embodying the invention and FIG. 2 is a cross section along the line 2-2 of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION The muffler 1 has a tubular casing 3, preferably oval in cross section, which is closed at one end by an inlet header 5 and at the other end by an outlet header 7 which are interconnected with the ends of the shell by means of interlocked joints 9. The inlet header 5 has an outwardly extending collar 11 and the outlet header 7 has an outwardly extending collar 13 which is aligned with the collar 11. Internal transverse partitions l5 and 17, which are spotwelded to the casing 3, having collars 19 and 21 which are adjacent the collars 11 and 13, respectively. An inlet bushing is supported in the collars 11 and 19 while an outlet bushing 25 is supported in the collars 13 and 21. The bushings 23 and 25 support opposite ends of a straight-through gas flow tube 27 so that gas entering the muffler 1 from an exhaust pipe 29 can flow straight through the muffler to the tailpipe 31. The partitions l5 and 17 divide the interior of the casing 3 into longitudinally separated chambers 33, 35, and 37. The gas flow tube 27 is perforated along most of its length within the relatively large volume central chamber 35, preferably by means of louvers 38.

The structure described is arranged, preferably, so that the gas flow tube 27 is offset from the centerline of the muffler 1 whereby there is a substantially larger space on one side of the gas flow tube than on the other within the casing 3. Disposed within the larger side of the casing 3, and extending parallel to the gas flow tube 27, are a plurality of open-ended secondary tubes 39 and 41 which are supported at opposite ends by collars 43 in partitions I5 and 17 to open into the chambers and 37 which are otherwise closed. The tubes 39 and 41 may be of the same or different diameters and are perforated along most of their length, preferably in longitudinal alignment with the perforations in tube 27, and perforations preferably being in the form of louvers 45. The louvers 45 act as inlet and outlet apertures for gas pulses leaving or entering the cylindrical chambers 47 and 49 formed by the interior of the tubes 39 and 41. The gas within the chambers 47 and 49 can expand longitudinally into the relatively large dead end chambers 33 and 37 which are preferably of somewhat different volumes as indicated in FIG. 1.

In operation, the gas flowing through the muffler I along the tube 27 encounters minimum resistance so that there is minimum horsepower loss due to back pressure. Soundwise, the energy of the gas pulses is dissipated by passing, in series, through the small cross section louvers into and from the various chambers 35, 47, and 49. Additionally, energy is lost by longitudinal expansion from tubes 39 and 41 into chambers 33 and 37. The silencing means is especially effective in medium and high frequencies and roughness. Attenuation of a low frequency may be achieved by locating the muffler 1 so that a central portion is positioned at an antinode or maximum pressure point of the frequency.

The overall performance of the muffler l is similar to packed mufflers favored by sports car drivers in that the high and medium frequencies are removed while the power sound of the lower frequencies is audible to some degree.

I claim: l. A mufi'ler comprising a housing having an inlet at one end and an outlet at the other end, a perforated straight-through gas flow tube connecting the inlet and outlet and providing a straight-through path for gas flow through the housing, a plurality of transversely separated perforated secondary tubes in the housing extending substantially parallel to each other and to the flow tube, and means supporting the secondary tubes in the housing.

2. A muffler as set forth in claim 1 wherein said means comprises transverse partitions in the housing.

3. A muffler as set forth in claim 2 wherein at least one of said partitions forms an end chamber in the housing, at least one of said secondary tubes having an open end communicating with the end chamber.

4. A muffler comprising a housing having an inlet at one end and an outlet at the other end, a pair of transverse partitions in the housing subdividing it into a pair of end chambers and a central chamber, a gas flow tube connecting the inlet and outlet and extending through all said chambers and being perforated along its length in the central chamber, and a pair of tubes perforated along their lengths in the central chamber and supported at opposite ends in said partitions.

5. A muffler as set forth in claim 4 wherein said pair of tubes are open at the ends into the end chambers.

6. A muffler as set forth in claim 5 wherein the tubes of said pair are transversely separated from and substantially parallel to each other and to the flow tube.

7. A mufiler as set forth in claim 4 wherein said tubes are perforated by means of louvers formed therein. 

1. A muffler comprising a housing having an inlet at one end and an outlet at the other end, a perforated straight-through gas flow tube connecting the inlet and outlet and providing a straight-through path for gas flow through the housing, a plurality of transversely separated perforated secondary tubes in the housing extending substantially parallel to each other and to the flow tube, and means supporting the secondary tubes in the housing.
 2. A muffler as set forth in claim 1 wherein said means comprises transverse partitions in the housing.
 3. A muffler as set forth in claim 2 wherein at least one of said partitions forms an end chamber in the housing, at least one of said secondary tubes having an open end communicating with the end chamber.
 4. A muffler comprising a housing having an inlet at one end and an outlet at the other end, a pair of transverse partitions in the housing subdividing it into a pair of end chambers and a central chamber, a gas flow tube connecting the inlet and outlet and extending through all said chambers and being perforated along its length in the central chamber, and a pair of tubes perforated along their lengths in the central chamber and supported at opposite ends in said partitions.
 5. A muffler as set forth in claim 4 wherein said pair of tubes are open at the ends into the end chambers.
 6. A muffler as set forth in claim 5 wherein the tubes of said pair are transversely separated from and substantially parallel to each other and to the flow tube.
 7. A muffler as set forth in claim 4 wherein said tubes are perforated by means of louvers formed therein. 